Where large deep-ocean waves break

Hans van Haren (1) , Andrea Cimatoribus (1) , Louis Gostiaux (2)

1 NIOZ - Royal Netherlands Institute for Sea Research
2 LMFA - Laboratoire de Mecanique des Fluides et d'Acoustique

Underwater topography like seamounts causes the breaking of large ‘internal waves’ with associated turbulent mixing strongly affecting the redistribution of sediment. Here, ocean-turbulence is characterized and quantified in the lowest 100 m of the water column at three nearby sites above the slope of a deep-ocean seamount. Moored high-resolution temperature sensors show very different turbulence generation mechanisms over 3 and 5 km horizontal separation distances. At the steepest slope, turbulence was 100-times more energetic than at the shallowest slope where turbulence was still ten times more energetic than found in the open-ocean, away from topography. The turbulence on this extensive slope is caused by slope steepness and nonlinear wave evolution, but not by bottom-friction, ‘critical’ internal tide reflection or lee-wave generation.

Domaines: Mécanique des fluides [physics.class-ph]

Hans van Haren, Andrea Cimatoribus, Louis Gostiaux. Where large deep-ocean waves break. Geophysical Research Letters, 2015, pp.GL063329. ⟨10.1002/2015GL063329⟩. ⟨hal-01137784⟩